1. Field of the Invention
The present invention relates to a reinforcing bar binding machine for binding reinforcing bars by feeding out a wire that is pulled out of a wire reel from a guide portion provided at a distal end of a binding machine main body to a periphery of the reinforcing bars so as to turn thereround in a loop-like fashion and twisting the wire.
2. Background Art
As is shown in Patent Documents 1 and 2, a reinforcing bar binding machine has a beak-like guide portion that is provided at a distal end thereof. Two reinforcing bars that intersect each other are inserted into the guide portion, a wire is pulled out of a wire reel, and the wire to which a curling-tendency is applied is fed out while being curled, whereby the wire is wound round the reinforcing bars in a loop-like fashion. After the wire has been so wound round the reinforcing bars, a terminating portion of the wire is cut by a cutter, and part of the looped wire is turned while being gripped by a twisting hook, whereby the reinforcing bars are bound together by the wire being so twisted.    [Patent Document 1] U.S. Pat. No. 5,279,336    [Patent Document 2] JP-A-11-169981
Incidentally, when binding the reinforcing bars, the guide portion of the reinforcing bar binding machine is inserted from one side (a front side) to the other side (a rear side) of an intersecting portion of two reinforcing bars, and after the two reinforcing bars are bound together, the guide portion is pulled out. It is common that an initiating end portion and a terminating end portion of the wire that is wound round the reinforcing bars lie in a position which is away from a twisted portion, and both the end portions never fail to be free. Consequently, normally, as is shown in FIG. 7(a), two end portions 105a, 105b of a wire 105 lie on an opposite side to a side where a twisted portion 105c lies. However, when the wire is twisted, there occurs from time to time a case in which one or both of the end portion of the wire project laterally due to the effect of twisting the wire. Then, when the reinforcing bar binding machine is pulled back to disengage the guide portion from the reinforcing bar after the twisting of the wire is completed, there occurs from time to time a case in which as is shown in FIG. 7(b), either of both of the two end portions 105a, 105b of the wire 105 which are made free are caught by the guide portion or the like and are then caused to move to a twisted portion 105c side of the reinforcing bar together with the reinforcing bar binding machine. As this occurs, since the end portion or end portions of the wire project to the twisted portion side to thereby be away from the reinforcing bar, not only does the external appearance of the reinforcing bar get worse, but also when concrete is placed in this state, there occurs from time to time a case in which the end portion or end portions of the wire project from a surface of the concrete so placed. When the wire is exposed from the concrete surface, rainwater infiltrates into an interior of the concrete through a gap between the wire and the concrete, causing cracks therein.
To deal with this, a mechanism is considered in which the wire is deformed to be held by the cutter and a distal end portion of the guide portion. According to this configuration, since the terminating end portion of the wire is held by the guide portion, when the guide portion is pulled out after the reinforcing bar are bound together, the initiating end portion of the wire is held down by the terminating end portion of the wire, whereby both the end portions can be kept staying on the rear side of the reinforcing bar.
However, when the amount of wire remaining in the wire reel reaches almost zero and an interval between the terminating end portion of the wire used last and an end portion of the wire remaining on the wire reel side is short, there occurs from time to time a case in which the remaining wire piece jams while being caught by the cutter and the distal end portion of the guide portion.
Since when the wire jams, the wire reel cannot be replaced by a new wire reel so as to feed out a wire, the guide portion has to be disassembled to remove the wire piece.
Further, in the conventional reinforcing bar binding machine, as is shown in Patent Documents 3, 4, curl guides are disposed vertically for applying a curling-tendency on a wire to curl the wire. A movable curl guide is provided so as to be opened and closed, and by the movable curl guide being designed to be opened and closed, a construction is enabled in which reinforcing bar which are bound together are easily removed from a binding machine main body. In addition, the opening and closing construction has a function as a safety device. When the movable curl guide is opened, it is judged that the finger or fingers of the operator or a tool is placed between the curl guides for maintenance or an abnormal state is occurring in which something jams, and the binding machine is designed not to operate. Since an opening or closing signal of the movable curl guide is sent to the binding machine main body, an opening becomes necessary which links an interior with an exterior of the binding machine main body. In addition, since a sensor for detecting the movable curl guide is disposed in the interior of the binding machine main body so as not to be influenced by dust, impact and disturbance, a signal is transmitted from the exterior to the interior of the binding machine main body by a mechanical means. Because of this, a relatively large opening is formed in a signal transmission portion of the binding machine main body.    [Patent Document 3] U.S. Pat. No. 5,956,989    [Patent Document 4] JP-A-09-165006
In the conventional reinforcing bar binding machine described above, when the movable curl guide is closed, the opening is also closed by a curl guide cover, and therefore, a foreign matter such as a small piece of wire is made difficult to enter the binding machine main body. However, when initializing is implemented, a wire is twisted to be cut or a wire reel becomes empty, there occurs from time to time a case in which a small piece of wire falls in the movable curl guide. Since when the curl guide is opened, an opening is produced between the movable curl guide and the curl guide cover, the cut small piece of wire sometimes enters the interior of the binding machine main body. In addition, since a total closure is not always provided between the movable curl guide and the curl guide cover but a small gap is formed therebetween, when the binding machine is used while being oriented upwards or when a jamming wire is attempted to be removed, there occurs from time to time a case in which the cut small piece of wire slides down on the movable curl guide to enter the interior of the binding machine main body from the gap.
In the event that the wire piece enters the binding machine main body, there is a possibility that a problem is caused that the wire piece gets stuck in a movable part, the wire piece enters the interior of a motor to lock the motor, or the detection by a magnetic sensor is delayed, leading to an operation failure of the reinforcing bar binding machine.